// webpack的配置文件
'use strict'//开启严格模式
//遵守nodejs的Commonjs规范的导包方式
//--导入 require()
//--导出 module.exports || exports
const path = require('path')//path操作路径的模块
//导入项目的配置文件setting。js文件中的配置
const defaultSettings = require('./src/settings.js')

//传入的相对路径变成绝对路径,dir接收的是相对路径
function resolve(dir) {
  //——dirname:获取当前文件所在目录的绝对路径
  return path.join(__dirname, dir)
}

//保存网页的标题
const name = defaultSettings.title || 'vue Admin Template' // page title

//保存项目启动的端口号
const port = process.env.port || process.env.npm_config_port || 9528 // dev port
let externals = {}
let cdn = { css: [], js: [] }
const isProduction = process.env.NODE_ENV === 'production' // 判断是否是生产环境
if (isProduction) {
  externals = {
    //左边包名，导入的时候的包名
    'vue': 'Vue',
    'element-ui': 'ELEMENT',
    'xlsx': 'XLSX'
  }
  //存储外链的地址
  cdn = {
    css: [
      'https://lib.baomitu.com/element-ui/2.15.10/theme-chalk/index.min.css' // element-ui css 样式表
    ],
    js: [
      // vue must at first!
      'https://lib.baomitu.com/vue/2.6.10/vue.min.js', // vuejs
      'https://lib.baomitu.com/element-ui/2.13.2/index.js', // element-ui js
      'https://lib.baomitu.com/xlsx/0.16.0/xlsx.min.js', // xlsx
    ]
  }
}
//脚手架vue-cli相关配置
module.exports = {
  //配置生产的资源index.html在什么环境下打开运行
  //默认'/'只能在服务器环境下运行,任何环境下运行可以将值设置位'./'
  publicPath: './',
  outputDir: 'dist',  //打包后导出资源目录的名称
  assetsDir: 'static',//打包后导出资源目录的名称中存储静态文件的目录 js，css,img等等
  lintOnSave: process.env.NODE_ENV === 'development', //是否开启eslint检查
  productionSourceMap: false,  //是否开启map映射
  //  脚手架提供服务器相关配置
  devServer: {
    port: port,  //设置端口号
    open: true,  //浏览器是否自动打开
    overlay: {  //overlay：设置错误代码的等级是否在浏览器显示
      warnings: false,
      errors: true
    },
    //配置代理服务器
    proxy: {
      '/api': {
        target: 'http://192.168.104.26:3000'
      }
    }
  },
  //webpack相关的配置 ,对象配置
  configureWebpack: {
    // provide the app's title in webpack's name field, so that
    // it can be accessed in index.html to inject the correct title.
    name: name,
    //添加包的排除项
    externals: externals,
    resolve: {
      alias: {
        '@': resolve('src')
      }
    }
  },
  //webpack相关的配置 ,函数配置
  chainWebpack(config) {

    config.plugin('html').tap(args => {
      args[0].cdn = cdn // 配置cdn给插件
      return args
    })
    // 省略其他...

    //打包去除consle.log打印
    config.optimization.minimizer('terser').tap((args) => {
      args[0].terserOptions.compress.drop_console = true
      return args
    })
    // it can improve the speed of the first screen, it is recommended to turn on preload
    config.plugin('preload').tap(() => [
      {
        rel: 'preload',
        // to ignore runtime.js
        // https://github.com/vuejs/vue-cli/blob/dev/packages/@vue/cli-service/lib/config/app.js#L171
        fileBlacklist: [/\.map$/, /hot-update\.js$/, /runtime\..*\.js$/],
        include: 'initial'
      }
    ])

    // when there are many pages, it will cause too many meaningless requests
    config.plugins.delete('prefetch')

    // set svg-sprite-loader
    //配置svg的loader 对于svg文件进行打包处理svg-sprite-loader
    config.module
      .rule('svg')
      .exclude.add(resolve('src/icons'))
      .end()
    config.module
      .rule('icons')
      .test(/\.svg$/)
      .include.add(resolve('src/icons'))
      .end()
      .use('svg-sprite-loader')
      .loader('svg-sprite-loader')
      .options({
        symbolId: 'icon-[name]'
      })
      .end()

    config
      .when(process.env.NODE_ENV !== 'development',
        config => {
          config
            .plugin('ScriptExtHtmlWebpackPlugin')
            .after('html')
            .use('script-ext-html-webpack-plugin', [{
              // `runtime` must same as runtimeChunk name. default is `runtime`
              inline: /runtime\..*\.js$/
            }])
            .end()
          config
            .optimization.splitChunks({
              chunks: 'all',
              cacheGroups: {
                libs: {
                  name: 'chunk-libs',
                  test: /[\\/]node_modules[\\/]/,
                  priority: 10,
                  chunks: 'initial' // only package third parties that are initially dependent
                },
                elementUI: {
                  name: 'chunk-elementUI', // split elementUI into a single package
                  priority: 20, // the weight needs to be larger than libs and app or it will be packaged into libs or app
                  test: /[\\/]node_modules[\\/]_?element-ui(.*)/ // in order to adapt to cnpm
                },
                commons: {
                  name: 'chunk-commons',
                  test: resolve('src/components'), // can customize your rules
                  minChunks: 3, //  minimum common number
                  priority: 5,
                  reuseExistingChunk: true
                }
              }
            })
          // https:// webpack.js.org/configuration/optimization/#optimizationruntimechunk
          config.optimization.runtimeChunk('single')
        }
      )
  }
}
